Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/locks.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 2 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 2 months ago) by niro
File MIME type: text/plain
File size: 55588 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* |
2 | * linux/fs/locks.c |
3 | * |
4 | * Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls. |
5 | * Doug Evans (dje@spiff.uucp), August 07, 1992 |
6 | * |
7 | * Deadlock detection added. |
8 | * FIXME: one thing isn't handled yet: |
9 | * - mandatory locks (requires lots of changes elsewhere) |
10 | * Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994. |
11 | * |
12 | * Miscellaneous edits, and a total rewrite of posix_lock_file() code. |
13 | * Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994 |
14 | * |
15 | * Converted file_lock_table to a linked list from an array, which eliminates |
16 | * the limits on how many active file locks are open. |
17 | * Chad Page (pageone@netcom.com), November 27, 1994 |
18 | * |
19 | * Removed dependency on file descriptors. dup()'ed file descriptors now |
20 | * get the same locks as the original file descriptors, and a close() on |
21 | * any file descriptor removes ALL the locks on the file for the current |
22 | * process. Since locks still depend on the process id, locks are inherited |
23 | * after an exec() but not after a fork(). This agrees with POSIX, and both |
24 | * BSD and SVR4 practice. |
25 | * Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995 |
26 | * |
27 | * Scrapped free list which is redundant now that we allocate locks |
28 | * dynamically with kmalloc()/kfree(). |
29 | * Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995 |
30 | * |
31 | * Implemented two lock personalities - FL_FLOCK and FL_POSIX. |
32 | * |
33 | * FL_POSIX locks are created with calls to fcntl() and lockf() through the |
34 | * fcntl() system call. They have the semantics described above. |
35 | * |
36 | * FL_FLOCK locks are created with calls to flock(), through the flock() |
37 | * system call, which is new. Old C libraries implement flock() via fcntl() |
38 | * and will continue to use the old, broken implementation. |
39 | * |
40 | * FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated |
41 | * with a file pointer (filp). As a result they can be shared by a parent |
42 | * process and its children after a fork(). They are removed when the last |
43 | * file descriptor referring to the file pointer is closed (unless explicitly |
44 | * unlocked). |
45 | * |
46 | * FL_FLOCK locks never deadlock, an existing lock is always removed before |
47 | * upgrading from shared to exclusive (or vice versa). When this happens |
48 | * any processes blocked by the current lock are woken up and allowed to |
49 | * run before the new lock is applied. |
50 | * Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995 |
51 | * |
52 | * Removed some race conditions in flock_lock_file(), marked other possible |
53 | * races. Just grep for FIXME to see them. |
54 | * Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996. |
55 | * |
56 | * Addressed Dmitry's concerns. Deadlock checking no longer recursive. |
57 | * Lock allocation changed to GFP_ATOMIC as we can't afford to sleep |
58 | * once we've checked for blocking and deadlocking. |
59 | * Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996. |
60 | * |
61 | * Initial implementation of mandatory locks. SunOS turned out to be |
62 | * a rotten model, so I implemented the "obvious" semantics. |
63 | * See 'Documentation/mandatory.txt' for details. |
64 | * Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996. |
65 | * |
66 | * Don't allow mandatory locks on mmap()'ed files. Added simple functions to |
67 | * check if a file has mandatory locks, used by mmap(), open() and creat() to |
68 | * see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference |
69 | * Manual, Section 2. |
70 | * Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996. |
71 | * |
72 | * Tidied up block list handling. Added '/proc/locks' interface. |
73 | * Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996. |
74 | * |
75 | * Fixed deadlock condition for pathological code that mixes calls to |
76 | * flock() and fcntl(). |
77 | * Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996. |
78 | * |
79 | * Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use |
80 | * for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to |
81 | * guarantee sensible behaviour in the case where file system modules might |
82 | * be compiled with different options than the kernel itself. |
83 | * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. |
84 | * |
85 | * Added a couple of missing wake_up() calls. Thanks to Thomas Meckel |
86 | * (Thomas.Meckel@mni.fh-giessen.de) for spotting this. |
87 | * Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996. |
88 | * |
89 | * Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK |
90 | * locks. Changed process synchronisation to avoid dereferencing locks that |
91 | * have already been freed. |
92 | * Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996. |
93 | * |
94 | * Made the block list a circular list to minimise searching in the list. |
95 | * Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996. |
96 | * |
97 | * Made mandatory locking a mount option. Default is not to allow mandatory |
98 | * locking. |
99 | * Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996. |
100 | * |
101 | * Some adaptations for NFS support. |
102 | * Olaf Kirch (okir@monad.swb.de), Dec 1996, |
103 | * |
104 | * Fixed /proc/locks interface so that we can't overrun the buffer we are handed. |
105 | * Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997. |
106 | * |
107 | * Use slab allocator instead of kmalloc/kfree. |
108 | * Use generic list implementation from <linux/list.h>. |
109 | * Sped up posix_locks_deadlock by only considering blocked locks. |
110 | * Matthew Wilcox <willy@debian.org>, March, 2000. |
111 | * |
112 | * Leases and LOCK_MAND |
113 | * Matthew Wilcox <willy@debian.org>, June, 2000. |
114 | * Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000. |
115 | */ |
116 | |
117 | #include <linux/capability.h> |
118 | #include <linux/file.h> |
119 | #include <linux/fs.h> |
120 | #include <linux/init.h> |
121 | #include <linux/module.h> |
122 | #include <linux/security.h> |
123 | #include <linux/slab.h> |
124 | #include <linux/smp_lock.h> |
125 | #include <linux/syscalls.h> |
126 | #include <linux/time.h> |
127 | |
128 | #include <asm/semaphore.h> |
129 | #include <asm/uaccess.h> |
130 | |
131 | #define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) |
132 | #define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) |
133 | #define IS_LEASE(fl) (fl->fl_flags & FL_LEASE) |
134 | |
135 | int leases_enable = 1; |
136 | int lease_break_time = 45; |
137 | |
138 | #define for_each_lock(inode, lockp) \ |
139 | for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next) |
140 | |
141 | LIST_HEAD(file_lock_list); |
142 | |
143 | EXPORT_SYMBOL(file_lock_list); |
144 | |
145 | static LIST_HEAD(blocked_list); |
146 | |
147 | static kmem_cache_t *filelock_cache; |
148 | |
149 | /* Allocate an empty lock structure. */ |
150 | static struct file_lock *locks_alloc_lock(void) |
151 | { |
152 | return kmem_cache_alloc(filelock_cache, SLAB_KERNEL); |
153 | } |
154 | |
155 | /* Free a lock which is not in use. */ |
156 | static inline void locks_free_lock(struct file_lock *fl) |
157 | { |
158 | if (fl == NULL) { |
159 | BUG(); |
160 | return; |
161 | } |
162 | if (waitqueue_active(&fl->fl_wait)) |
163 | panic("Attempting to free lock with active wait queue"); |
164 | |
165 | if (!list_empty(&fl->fl_block)) |
166 | panic("Attempting to free lock with active block list"); |
167 | |
168 | if (!list_empty(&fl->fl_link)) |
169 | panic("Attempting to free lock on active lock list"); |
170 | |
171 | if (fl->fl_ops) { |
172 | if (fl->fl_ops->fl_release_private) |
173 | fl->fl_ops->fl_release_private(fl); |
174 | fl->fl_ops = NULL; |
175 | } |
176 | |
177 | if (fl->fl_lmops) { |
178 | if (fl->fl_lmops->fl_release_private) |
179 | fl->fl_lmops->fl_release_private(fl); |
180 | fl->fl_lmops = NULL; |
181 | } |
182 | |
183 | kmem_cache_free(filelock_cache, fl); |
184 | } |
185 | |
186 | void locks_init_lock(struct file_lock *fl) |
187 | { |
188 | INIT_LIST_HEAD(&fl->fl_link); |
189 | INIT_LIST_HEAD(&fl->fl_block); |
190 | init_waitqueue_head(&fl->fl_wait); |
191 | fl->fl_next = NULL; |
192 | fl->fl_fasync = NULL; |
193 | fl->fl_owner = NULL; |
194 | fl->fl_pid = 0; |
195 | fl->fl_file = NULL; |
196 | fl->fl_flags = 0; |
197 | fl->fl_type = 0; |
198 | fl->fl_start = fl->fl_end = 0; |
199 | fl->fl_ops = NULL; |
200 | fl->fl_lmops = NULL; |
201 | } |
202 | |
203 | EXPORT_SYMBOL(locks_init_lock); |
204 | |
205 | /* |
206 | * Initialises the fields of the file lock which are invariant for |
207 | * free file_locks. |
208 | */ |
209 | static void init_once(void *foo, kmem_cache_t *cache, unsigned long flags) |
210 | { |
211 | struct file_lock *lock = (struct file_lock *) foo; |
212 | |
213 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) != |
214 | SLAB_CTOR_CONSTRUCTOR) |
215 | return; |
216 | |
217 | locks_init_lock(lock); |
218 | } |
219 | |
220 | /* |
221 | * Initialize a new lock from an existing file_lock structure. |
222 | */ |
223 | void locks_copy_lock(struct file_lock *new, struct file_lock *fl) |
224 | { |
225 | new->fl_owner = fl->fl_owner; |
226 | new->fl_pid = fl->fl_pid; |
227 | new->fl_file = fl->fl_file; |
228 | new->fl_flags = fl->fl_flags; |
229 | new->fl_type = fl->fl_type; |
230 | new->fl_start = fl->fl_start; |
231 | new->fl_end = fl->fl_end; |
232 | new->fl_ops = fl->fl_ops; |
233 | new->fl_lmops = fl->fl_lmops; |
234 | if (fl->fl_ops && fl->fl_ops->fl_copy_lock) |
235 | fl->fl_ops->fl_copy_lock(new, fl); |
236 | if (fl->fl_lmops && fl->fl_lmops->fl_copy_lock) |
237 | fl->fl_lmops->fl_copy_lock(new, fl); |
238 | } |
239 | |
240 | EXPORT_SYMBOL(locks_copy_lock); |
241 | |
242 | static inline int flock_translate_cmd(int cmd) { |
243 | if (cmd & LOCK_MAND) |
244 | return cmd & (LOCK_MAND | LOCK_RW); |
245 | switch (cmd) { |
246 | case LOCK_SH: |
247 | return F_RDLCK; |
248 | case LOCK_EX: |
249 | return F_WRLCK; |
250 | case LOCK_UN: |
251 | return F_UNLCK; |
252 | } |
253 | return -EINVAL; |
254 | } |
255 | |
256 | /* Fill in a file_lock structure with an appropriate FLOCK lock. */ |
257 | static int flock_make_lock(struct file *filp, struct file_lock **lock, |
258 | unsigned int cmd) |
259 | { |
260 | struct file_lock *fl; |
261 | int type = flock_translate_cmd(cmd); |
262 | if (type < 0) |
263 | return type; |
264 | |
265 | fl = locks_alloc_lock(); |
266 | if (fl == NULL) |
267 | return -ENOMEM; |
268 | |
269 | fl->fl_file = filp; |
270 | fl->fl_pid = current->tgid; |
271 | fl->fl_flags = FL_FLOCK; |
272 | fl->fl_type = type; |
273 | fl->fl_end = OFFSET_MAX; |
274 | |
275 | *lock = fl; |
276 | return 0; |
277 | } |
278 | |
279 | static int assign_type(struct file_lock *fl, int type) |
280 | { |
281 | switch (type) { |
282 | case F_RDLCK: |
283 | case F_WRLCK: |
284 | case F_UNLCK: |
285 | fl->fl_type = type; |
286 | break; |
287 | default: |
288 | return -EINVAL; |
289 | } |
290 | return 0; |
291 | } |
292 | |
293 | /* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX |
294 | * style lock. |
295 | */ |
296 | static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, |
297 | struct flock *l) |
298 | { |
299 | off_t start, end; |
300 | |
301 | switch (l->l_whence) { |
302 | case 0: /*SEEK_SET*/ |
303 | start = 0; |
304 | break; |
305 | case 1: /*SEEK_CUR*/ |
306 | start = filp->f_pos; |
307 | break; |
308 | case 2: /*SEEK_END*/ |
309 | start = i_size_read(filp->f_dentry->d_inode); |
310 | break; |
311 | default: |
312 | return -EINVAL; |
313 | } |
314 | |
315 | /* POSIX-1996 leaves the case l->l_len < 0 undefined; |
316 | POSIX-2001 defines it. */ |
317 | start += l->l_start; |
318 | end = start + l->l_len - 1; |
319 | if (l->l_len < 0) { |
320 | end = start - 1; |
321 | start += l->l_len; |
322 | } |
323 | |
324 | if (start < 0) |
325 | return -EINVAL; |
326 | if (l->l_len > 0 && end < 0) |
327 | return -EOVERFLOW; |
328 | |
329 | fl->fl_start = start; /* we record the absolute position */ |
330 | fl->fl_end = end; |
331 | if (l->l_len == 0) |
332 | fl->fl_end = OFFSET_MAX; |
333 | |
334 | fl->fl_owner = current->files; |
335 | fl->fl_pid = current->tgid; |
336 | fl->fl_file = filp; |
337 | fl->fl_flags = FL_POSIX; |
338 | fl->fl_ops = NULL; |
339 | fl->fl_lmops = NULL; |
340 | |
341 | return assign_type(fl, l->l_type); |
342 | } |
343 | |
344 | #if BITS_PER_LONG == 32 |
345 | static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, |
346 | struct flock64 *l) |
347 | { |
348 | loff_t start; |
349 | |
350 | switch (l->l_whence) { |
351 | case 0: /*SEEK_SET*/ |
352 | start = 0; |
353 | break; |
354 | case 1: /*SEEK_CUR*/ |
355 | start = filp->f_pos; |
356 | break; |
357 | case 2: /*SEEK_END*/ |
358 | start = i_size_read(filp->f_dentry->d_inode); |
359 | break; |
360 | default: |
361 | return -EINVAL; |
362 | } |
363 | |
364 | if (((start += l->l_start) < 0) || (l->l_len < 0)) |
365 | return -EINVAL; |
366 | fl->fl_end = start + l->l_len - 1; |
367 | if (l->l_len > 0 && fl->fl_end < 0) |
368 | return -EOVERFLOW; |
369 | fl->fl_start = start; /* we record the absolute position */ |
370 | if (l->l_len == 0) |
371 | fl->fl_end = OFFSET_MAX; |
372 | |
373 | fl->fl_owner = current->files; |
374 | fl->fl_pid = current->tgid; |
375 | fl->fl_file = filp; |
376 | fl->fl_flags = FL_POSIX; |
377 | fl->fl_ops = NULL; |
378 | fl->fl_lmops = NULL; |
379 | |
380 | switch (l->l_type) { |
381 | case F_RDLCK: |
382 | case F_WRLCK: |
383 | case F_UNLCK: |
384 | fl->fl_type = l->l_type; |
385 | break; |
386 | default: |
387 | return -EINVAL; |
388 | } |
389 | |
390 | return (0); |
391 | } |
392 | #endif |
393 | |
394 | /* default lease lock manager operations */ |
395 | static void lease_break_callback(struct file_lock *fl) |
396 | { |
397 | kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); |
398 | } |
399 | |
400 | static void lease_release_private_callback(struct file_lock *fl) |
401 | { |
402 | if (!fl->fl_file) |
403 | return; |
404 | |
405 | f_delown(fl->fl_file); |
406 | fl->fl_file->f_owner.signum = 0; |
407 | } |
408 | |
409 | static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try) |
410 | { |
411 | return fl->fl_file == try->fl_file; |
412 | } |
413 | |
414 | static struct lock_manager_operations lease_manager_ops = { |
415 | .fl_break = lease_break_callback, |
416 | .fl_release_private = lease_release_private_callback, |
417 | .fl_mylease = lease_mylease_callback, |
418 | .fl_change = lease_modify, |
419 | }; |
420 | |
421 | /* |
422 | * Initialize a lease, use the default lock manager operations |
423 | */ |
424 | static int lease_init(struct file *filp, int type, struct file_lock *fl) |
425 | { |
426 | fl->fl_owner = current->files; |
427 | fl->fl_pid = current->tgid; |
428 | |
429 | fl->fl_file = filp; |
430 | fl->fl_flags = FL_LEASE; |
431 | if (assign_type(fl, type) != 0) { |
432 | locks_free_lock(fl); |
433 | return -EINVAL; |
434 | } |
435 | fl->fl_start = 0; |
436 | fl->fl_end = OFFSET_MAX; |
437 | fl->fl_ops = NULL; |
438 | fl->fl_lmops = &lease_manager_ops; |
439 | return 0; |
440 | } |
441 | |
442 | /* Allocate a file_lock initialised to this type of lease */ |
443 | static int lease_alloc(struct file *filp, int type, struct file_lock **flp) |
444 | { |
445 | struct file_lock *fl = locks_alloc_lock(); |
446 | int error; |
447 | |
448 | if (fl == NULL) |
449 | return -ENOMEM; |
450 | |
451 | error = lease_init(filp, type, fl); |
452 | if (error) |
453 | return error; |
454 | *flp = fl; |
455 | return 0; |
456 | } |
457 | |
458 | /* Check if two locks overlap each other. |
459 | */ |
460 | static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) |
461 | { |
462 | return ((fl1->fl_end >= fl2->fl_start) && |
463 | (fl2->fl_end >= fl1->fl_start)); |
464 | } |
465 | |
466 | /* |
467 | * Check whether two locks have the same owner. |
468 | */ |
469 | static inline int |
470 | posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
471 | { |
472 | if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner) |
473 | return fl2->fl_lmops == fl1->fl_lmops && |
474 | fl1->fl_lmops->fl_compare_owner(fl1, fl2); |
475 | return fl1->fl_owner == fl2->fl_owner; |
476 | } |
477 | |
478 | /* Remove waiter from blocker's block list. |
479 | * When blocker ends up pointing to itself then the list is empty. |
480 | */ |
481 | static inline void __locks_delete_block(struct file_lock *waiter) |
482 | { |
483 | list_del_init(&waiter->fl_block); |
484 | list_del_init(&waiter->fl_link); |
485 | waiter->fl_next = NULL; |
486 | } |
487 | |
488 | /* |
489 | */ |
490 | static void locks_delete_block(struct file_lock *waiter) |
491 | { |
492 | lock_kernel(); |
493 | __locks_delete_block(waiter); |
494 | unlock_kernel(); |
495 | } |
496 | |
497 | /* Insert waiter into blocker's block list. |
498 | * We use a circular list so that processes can be easily woken up in |
499 | * the order they blocked. The documentation doesn't require this but |
500 | * it seems like the reasonable thing to do. |
501 | */ |
502 | static void locks_insert_block(struct file_lock *blocker, |
503 | struct file_lock *waiter) |
504 | { |
505 | if (!list_empty(&waiter->fl_block)) { |
506 | printk(KERN_ERR "locks_insert_block: removing duplicated lock " |
507 | "(pid=%d %Ld-%Ld type=%d)\n", waiter->fl_pid, |
508 | waiter->fl_start, waiter->fl_end, waiter->fl_type); |
509 | __locks_delete_block(waiter); |
510 | } |
511 | list_add_tail(&waiter->fl_block, &blocker->fl_block); |
512 | waiter->fl_next = blocker; |
513 | if (IS_POSIX(blocker)) |
514 | list_add(&waiter->fl_link, &blocked_list); |
515 | } |
516 | |
517 | /* Wake up processes blocked waiting for blocker. |
518 | * If told to wait then schedule the processes until the block list |
519 | * is empty, otherwise empty the block list ourselves. |
520 | */ |
521 | static void locks_wake_up_blocks(struct file_lock *blocker) |
522 | { |
523 | while (!list_empty(&blocker->fl_block)) { |
524 | struct file_lock *waiter = list_entry(blocker->fl_block.next, |
525 | struct file_lock, fl_block); |
526 | __locks_delete_block(waiter); |
527 | if (waiter->fl_lmops && waiter->fl_lmops->fl_notify) |
528 | waiter->fl_lmops->fl_notify(waiter); |
529 | else |
530 | wake_up(&waiter->fl_wait); |
531 | } |
532 | } |
533 | |
534 | /* Insert file lock fl into an inode's lock list at the position indicated |
535 | * by pos. At the same time add the lock to the global file lock list. |
536 | */ |
537 | static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl) |
538 | { |
539 | list_add(&fl->fl_link, &file_lock_list); |
540 | |
541 | /* insert into file's list */ |
542 | fl->fl_next = *pos; |
543 | *pos = fl; |
544 | |
545 | if (fl->fl_ops && fl->fl_ops->fl_insert) |
546 | fl->fl_ops->fl_insert(fl); |
547 | } |
548 | |
549 | /* |
550 | * Delete a lock and then free it. |
551 | * Wake up processes that are blocked waiting for this lock, |
552 | * notify the FS that the lock has been cleared and |
553 | * finally free the lock. |
554 | */ |
555 | static void locks_delete_lock(struct file_lock **thisfl_p) |
556 | { |
557 | struct file_lock *fl = *thisfl_p; |
558 | |
559 | *thisfl_p = fl->fl_next; |
560 | fl->fl_next = NULL; |
561 | list_del_init(&fl->fl_link); |
562 | |
563 | fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); |
564 | if (fl->fl_fasync != NULL) { |
565 | printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); |
566 | fl->fl_fasync = NULL; |
567 | } |
568 | |
569 | if (fl->fl_ops && fl->fl_ops->fl_remove) |
570 | fl->fl_ops->fl_remove(fl); |
571 | |
572 | locks_wake_up_blocks(fl); |
573 | locks_free_lock(fl); |
574 | } |
575 | |
576 | /* Determine if lock sys_fl blocks lock caller_fl. Common functionality |
577 | * checks for shared/exclusive status of overlapping locks. |
578 | */ |
579 | static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
580 | { |
581 | if (sys_fl->fl_type == F_WRLCK) |
582 | return 1; |
583 | if (caller_fl->fl_type == F_WRLCK) |
584 | return 1; |
585 | return 0; |
586 | } |
587 | |
588 | /* Determine if lock sys_fl blocks lock caller_fl. POSIX specific |
589 | * checking before calling the locks_conflict(). |
590 | */ |
591 | static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
592 | { |
593 | /* POSIX locks owned by the same process do not conflict with |
594 | * each other. |
595 | */ |
596 | if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl)) |
597 | return (0); |
598 | |
599 | /* Check whether they overlap */ |
600 | if (!locks_overlap(caller_fl, sys_fl)) |
601 | return 0; |
602 | |
603 | return (locks_conflict(caller_fl, sys_fl)); |
604 | } |
605 | |
606 | /* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific |
607 | * checking before calling the locks_conflict(). |
608 | */ |
609 | static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl) |
610 | { |
611 | /* FLOCK locks referring to the same filp do not conflict with |
612 | * each other. |
613 | */ |
614 | if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file)) |
615 | return (0); |
616 | if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND)) |
617 | return 0; |
618 | |
619 | return (locks_conflict(caller_fl, sys_fl)); |
620 | } |
621 | |
622 | static int interruptible_sleep_on_locked(wait_queue_head_t *fl_wait, int timeout) |
623 | { |
624 | int result = 0; |
625 | DECLARE_WAITQUEUE(wait, current); |
626 | |
627 | __set_current_state(TASK_INTERRUPTIBLE); |
628 | add_wait_queue(fl_wait, &wait); |
629 | if (timeout == 0) |
630 | schedule(); |
631 | else |
632 | result = schedule_timeout(timeout); |
633 | if (signal_pending(current)) |
634 | result = -ERESTARTSYS; |
635 | remove_wait_queue(fl_wait, &wait); |
636 | __set_current_state(TASK_RUNNING); |
637 | return result; |
638 | } |
639 | |
640 | static int locks_block_on_timeout(struct file_lock *blocker, struct file_lock *waiter, int time) |
641 | { |
642 | int result; |
643 | locks_insert_block(blocker, waiter); |
644 | result = interruptible_sleep_on_locked(&waiter->fl_wait, time); |
645 | __locks_delete_block(waiter); |
646 | return result; |
647 | } |
648 | |
649 | struct file_lock * |
650 | posix_test_lock(struct file *filp, struct file_lock *fl) |
651 | { |
652 | struct file_lock *cfl; |
653 | |
654 | lock_kernel(); |
655 | for (cfl = filp->f_dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) { |
656 | if (!IS_POSIX(cfl)) |
657 | continue; |
658 | if (posix_locks_conflict(cfl, fl)) |
659 | break; |
660 | } |
661 | unlock_kernel(); |
662 | |
663 | return (cfl); |
664 | } |
665 | |
666 | EXPORT_SYMBOL(posix_test_lock); |
667 | |
668 | /* This function tests for deadlock condition before putting a process to |
669 | * sleep. The detection scheme is no longer recursive. Recursive was neat, |
670 | * but dangerous - we risked stack corruption if the lock data was bad, or |
671 | * if the recursion was too deep for any other reason. |
672 | * |
673 | * We rely on the fact that a task can only be on one lock's wait queue |
674 | * at a time. When we find blocked_task on a wait queue we can re-search |
675 | * with blocked_task equal to that queue's owner, until either blocked_task |
676 | * isn't found, or blocked_task is found on a queue owned by my_task. |
677 | * |
678 | * Note: the above assumption may not be true when handling lock requests |
679 | * from a broken NFS client. But broken NFS clients have a lot more to |
680 | * worry about than proper deadlock detection anyway... --okir |
681 | */ |
682 | int posix_locks_deadlock(struct file_lock *caller_fl, |
683 | struct file_lock *block_fl) |
684 | { |
685 | struct list_head *tmp; |
686 | |
687 | next_task: |
688 | if (posix_same_owner(caller_fl, block_fl)) |
689 | return 1; |
690 | list_for_each(tmp, &blocked_list) { |
691 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); |
692 | if (posix_same_owner(fl, block_fl)) { |
693 | fl = fl->fl_next; |
694 | block_fl = fl; |
695 | goto next_task; |
696 | } |
697 | } |
698 | return 0; |
699 | } |
700 | |
701 | EXPORT_SYMBOL(posix_locks_deadlock); |
702 | |
703 | /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks |
704 | * at the head of the list, but that's secret knowledge known only to |
705 | * flock_lock_file and posix_lock_file. |
706 | */ |
707 | static int flock_lock_file(struct file *filp, struct file_lock *new_fl) |
708 | { |
709 | struct file_lock **before; |
710 | struct inode * inode = filp->f_dentry->d_inode; |
711 | int error = 0; |
712 | int found = 0; |
713 | |
714 | lock_kernel(); |
715 | for_each_lock(inode, before) { |
716 | struct file_lock *fl = *before; |
717 | if (IS_POSIX(fl)) |
718 | break; |
719 | if (IS_LEASE(fl)) |
720 | continue; |
721 | if (filp != fl->fl_file) |
722 | continue; |
723 | if (new_fl->fl_type == fl->fl_type) |
724 | goto out; |
725 | found = 1; |
726 | locks_delete_lock(before); |
727 | break; |
728 | } |
729 | unlock_kernel(); |
730 | |
731 | if (new_fl->fl_type == F_UNLCK) |
732 | return 0; |
733 | |
734 | /* |
735 | * If a higher-priority process was blocked on the old file lock, |
736 | * give it the opportunity to lock the file. |
737 | */ |
738 | if (found) |
739 | cond_resched(); |
740 | |
741 | lock_kernel(); |
742 | for_each_lock(inode, before) { |
743 | struct file_lock *fl = *before; |
744 | if (IS_POSIX(fl)) |
745 | break; |
746 | if (IS_LEASE(fl)) |
747 | continue; |
748 | if (!flock_locks_conflict(new_fl, fl)) |
749 | continue; |
750 | error = -EAGAIN; |
751 | if (new_fl->fl_flags & FL_SLEEP) { |
752 | locks_insert_block(fl, new_fl); |
753 | } |
754 | goto out; |
755 | } |
756 | locks_insert_lock(&inode->i_flock, new_fl); |
757 | error = 0; |
758 | |
759 | out: |
760 | unlock_kernel(); |
761 | return error; |
762 | } |
763 | |
764 | EXPORT_SYMBOL(posix_lock_file); |
765 | |
766 | static int __posix_lock_file(struct inode *inode, struct file_lock *request) |
767 | { |
768 | struct file_lock *fl; |
769 | struct file_lock *new_fl, *new_fl2; |
770 | struct file_lock *left = NULL; |
771 | struct file_lock *right = NULL; |
772 | struct file_lock **before; |
773 | int error, added = 0; |
774 | |
775 | /* |
776 | * We may need two file_lock structures for this operation, |
777 | * so we get them in advance to avoid races. |
778 | */ |
779 | new_fl = locks_alloc_lock(); |
780 | new_fl2 = locks_alloc_lock(); |
781 | |
782 | lock_kernel(); |
783 | if (request->fl_type != F_UNLCK) { |
784 | for_each_lock(inode, before) { |
785 | struct file_lock *fl = *before; |
786 | if (!IS_POSIX(fl)) |
787 | continue; |
788 | if (!posix_locks_conflict(request, fl)) |
789 | continue; |
790 | error = -EAGAIN; |
791 | if (!(request->fl_flags & FL_SLEEP)) |
792 | goto out; |
793 | error = -EDEADLK; |
794 | if (posix_locks_deadlock(request, fl)) |
795 | goto out; |
796 | error = -EAGAIN; |
797 | locks_insert_block(fl, request); |
798 | goto out; |
799 | } |
800 | } |
801 | |
802 | /* If we're just looking for a conflict, we're done. */ |
803 | error = 0; |
804 | if (request->fl_flags & FL_ACCESS) |
805 | goto out; |
806 | |
807 | error = -ENOLCK; /* "no luck" */ |
808 | if (!(new_fl && new_fl2)) |
809 | goto out; |
810 | |
811 | /* |
812 | * We've allocated the new locks in advance, so there are no |
813 | * errors possible (and no blocking operations) from here on. |
814 | * |
815 | * Find the first old lock with the same owner as the new lock. |
816 | */ |
817 | |
818 | before = &inode->i_flock; |
819 | |
820 | /* First skip locks owned by other processes. */ |
821 | while ((fl = *before) && (!IS_POSIX(fl) || |
822 | !posix_same_owner(request, fl))) { |
823 | before = &fl->fl_next; |
824 | } |
825 | |
826 | /* Process locks with this owner. */ |
827 | while ((fl = *before) && posix_same_owner(request, fl)) { |
828 | /* Detect adjacent or overlapping regions (if same lock type) |
829 | */ |
830 | if (request->fl_type == fl->fl_type) { |
831 | if (fl->fl_end < request->fl_start - 1) |
832 | goto next_lock; |
833 | /* If the next lock in the list has entirely bigger |
834 | * addresses than the new one, insert the lock here. |
835 | */ |
836 | if (fl->fl_start > request->fl_end + 1) |
837 | break; |
838 | |
839 | /* If we come here, the new and old lock are of the |
840 | * same type and adjacent or overlapping. Make one |
841 | * lock yielding from the lower start address of both |
842 | * locks to the higher end address. |
843 | */ |
844 | if (fl->fl_start > request->fl_start) |
845 | fl->fl_start = request->fl_start; |
846 | else |
847 | request->fl_start = fl->fl_start; |
848 | if (fl->fl_end < request->fl_end) |
849 | fl->fl_end = request->fl_end; |
850 | else |
851 | request->fl_end = fl->fl_end; |
852 | if (added) { |
853 | locks_delete_lock(before); |
854 | continue; |
855 | } |
856 | request = fl; |
857 | added = 1; |
858 | } |
859 | else { |
860 | /* Processing for different lock types is a bit |
861 | * more complex. |
862 | */ |
863 | if (fl->fl_end < request->fl_start) |
864 | goto next_lock; |
865 | if (fl->fl_start > request->fl_end) |
866 | break; |
867 | if (request->fl_type == F_UNLCK) |
868 | added = 1; |
869 | if (fl->fl_start < request->fl_start) |
870 | left = fl; |
871 | /* If the next lock in the list has a higher end |
872 | * address than the new one, insert the new one here. |
873 | */ |
874 | if (fl->fl_end > request->fl_end) { |
875 | right = fl; |
876 | break; |
877 | } |
878 | if (fl->fl_start >= request->fl_start) { |
879 | /* The new lock completely replaces an old |
880 | * one (This may happen several times). |
881 | */ |
882 | if (added) { |
883 | locks_delete_lock(before); |
884 | continue; |
885 | } |
886 | /* Replace the old lock with the new one. |
887 | * Wake up anybody waiting for the old one, |
888 | * as the change in lock type might satisfy |
889 | * their needs. |
890 | */ |
891 | locks_wake_up_blocks(fl); |
892 | fl->fl_start = request->fl_start; |
893 | fl->fl_end = request->fl_end; |
894 | fl->fl_type = request->fl_type; |
895 | fl->fl_u = request->fl_u; |
896 | request = fl; |
897 | added = 1; |
898 | } |
899 | } |
900 | /* Go on to next lock. |
901 | */ |
902 | next_lock: |
903 | before = &fl->fl_next; |
904 | } |
905 | |
906 | error = 0; |
907 | if (!added) { |
908 | if (request->fl_type == F_UNLCK) |
909 | goto out; |
910 | locks_copy_lock(new_fl, request); |
911 | locks_insert_lock(before, new_fl); |
912 | new_fl = NULL; |
913 | } |
914 | if (right) { |
915 | if (left == right) { |
916 | /* The new lock breaks the old one in two pieces, |
917 | * so we have to use the second new lock. |
918 | */ |
919 | left = new_fl2; |
920 | new_fl2 = NULL; |
921 | locks_copy_lock(left, right); |
922 | locks_insert_lock(before, left); |
923 | } |
924 | right->fl_start = request->fl_end + 1; |
925 | locks_wake_up_blocks(right); |
926 | } |
927 | if (left) { |
928 | left->fl_end = request->fl_start - 1; |
929 | locks_wake_up_blocks(left); |
930 | } |
931 | out: |
932 | unlock_kernel(); |
933 | /* |
934 | * Free any unused locks. |
935 | */ |
936 | if (new_fl) |
937 | locks_free_lock(new_fl); |
938 | if (new_fl2) |
939 | locks_free_lock(new_fl2); |
940 | return error; |
941 | } |
942 | |
943 | /** |
944 | * posix_lock_file - Apply a POSIX-style lock to a file |
945 | * @filp: The file to apply the lock to |
946 | * @fl: The lock to be applied |
947 | * |
948 | * Add a POSIX style lock to a file. |
949 | * We merge adjacent & overlapping locks whenever possible. |
950 | * POSIX locks are sorted by owner task, then by starting address |
951 | */ |
952 | int posix_lock_file(struct file *filp, struct file_lock *fl) |
953 | { |
954 | return __posix_lock_file(filp->f_dentry->d_inode, fl); |
955 | } |
956 | |
957 | /** |
958 | * posix_lock_file_wait - Apply a POSIX-style lock to a file |
959 | * @filp: The file to apply the lock to |
960 | * @fl: The lock to be applied |
961 | * |
962 | * Add a POSIX style lock to a file. |
963 | * We merge adjacent & overlapping locks whenever possible. |
964 | * POSIX locks are sorted by owner task, then by starting address |
965 | */ |
966 | int posix_lock_file_wait(struct file *filp, struct file_lock *fl) |
967 | { |
968 | int error; |
969 | might_sleep (); |
970 | for (;;) { |
971 | error = __posix_lock_file(filp->f_dentry->d_inode, fl); |
972 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) |
973 | break; |
974 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
975 | if (!error) |
976 | continue; |
977 | |
978 | locks_delete_block(fl); |
979 | break; |
980 | } |
981 | return error; |
982 | } |
983 | EXPORT_SYMBOL(posix_lock_file_wait); |
984 | |
985 | /** |
986 | * locks_mandatory_locked - Check for an active lock |
987 | * @inode: the file to check |
988 | * |
989 | * Searches the inode's list of locks to find any POSIX locks which conflict. |
990 | * This function is called from locks_verify_locked() only. |
991 | */ |
992 | int locks_mandatory_locked(struct inode *inode) |
993 | { |
994 | fl_owner_t owner = current->files; |
995 | struct file_lock *fl; |
996 | |
997 | /* |
998 | * Search the lock list for this inode for any POSIX locks. |
999 | */ |
1000 | lock_kernel(); |
1001 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
1002 | if (!IS_POSIX(fl)) |
1003 | continue; |
1004 | if (fl->fl_owner != owner) |
1005 | break; |
1006 | } |
1007 | unlock_kernel(); |
1008 | return fl ? -EAGAIN : 0; |
1009 | } |
1010 | |
1011 | /** |
1012 | * locks_mandatory_area - Check for a conflicting lock |
1013 | * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ |
1014 | * for shared |
1015 | * @inode: the file to check |
1016 | * @filp: how the file was opened (if it was) |
1017 | * @offset: start of area to check |
1018 | * @count: length of area to check |
1019 | * |
1020 | * Searches the inode's list of locks to find any POSIX locks which conflict. |
1021 | * This function is called from rw_verify_area() and |
1022 | * locks_verify_truncate(). |
1023 | */ |
1024 | int locks_mandatory_area(int read_write, struct inode *inode, |
1025 | struct file *filp, loff_t offset, |
1026 | size_t count) |
1027 | { |
1028 | struct file_lock fl; |
1029 | int error; |
1030 | |
1031 | locks_init_lock(&fl); |
1032 | fl.fl_owner = current->files; |
1033 | fl.fl_pid = current->tgid; |
1034 | fl.fl_file = filp; |
1035 | fl.fl_flags = FL_POSIX | FL_ACCESS; |
1036 | if (filp && !(filp->f_flags & O_NONBLOCK)) |
1037 | fl.fl_flags |= FL_SLEEP; |
1038 | fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK; |
1039 | fl.fl_start = offset; |
1040 | fl.fl_end = offset + count - 1; |
1041 | |
1042 | for (;;) { |
1043 | error = __posix_lock_file(inode, &fl); |
1044 | if (error != -EAGAIN) |
1045 | break; |
1046 | if (!(fl.fl_flags & FL_SLEEP)) |
1047 | break; |
1048 | error = wait_event_interruptible(fl.fl_wait, !fl.fl_next); |
1049 | if (!error) { |
1050 | /* |
1051 | * If we've been sleeping someone might have |
1052 | * changed the permissions behind our back. |
1053 | */ |
1054 | if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID) |
1055 | continue; |
1056 | } |
1057 | |
1058 | locks_delete_block(&fl); |
1059 | break; |
1060 | } |
1061 | |
1062 | return error; |
1063 | } |
1064 | |
1065 | EXPORT_SYMBOL(locks_mandatory_area); |
1066 | |
1067 | /* We already had a lease on this file; just change its type */ |
1068 | int lease_modify(struct file_lock **before, int arg) |
1069 | { |
1070 | struct file_lock *fl = *before; |
1071 | int error = assign_type(fl, arg); |
1072 | |
1073 | if (error) |
1074 | return error; |
1075 | locks_wake_up_blocks(fl); |
1076 | if (arg == F_UNLCK) |
1077 | locks_delete_lock(before); |
1078 | return 0; |
1079 | } |
1080 | |
1081 | EXPORT_SYMBOL(lease_modify); |
1082 | |
1083 | static void time_out_leases(struct inode *inode) |
1084 | { |
1085 | struct file_lock **before; |
1086 | struct file_lock *fl; |
1087 | |
1088 | before = &inode->i_flock; |
1089 | while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) { |
1090 | if ((fl->fl_break_time == 0) |
1091 | || time_before(jiffies, fl->fl_break_time)) { |
1092 | before = &fl->fl_next; |
1093 | continue; |
1094 | } |
1095 | printk(KERN_INFO "lease broken - owner pid = %d\n", fl->fl_pid); |
1096 | lease_modify(before, fl->fl_type & ~F_INPROGRESS); |
1097 | if (fl == *before) /* lease_modify may have freed fl */ |
1098 | before = &fl->fl_next; |
1099 | } |
1100 | } |
1101 | |
1102 | /** |
1103 | * __break_lease - revoke all outstanding leases on file |
1104 | * @inode: the inode of the file to return |
1105 | * @mode: the open mode (read or write) |
1106 | * |
1107 | * break_lease (inlined for speed) has checked there already |
1108 | * is a lease on this file. Leases are broken on a call to open() |
1109 | * or truncate(). This function can sleep unless you |
1110 | * specified %O_NONBLOCK to your open(). |
1111 | */ |
1112 | int __break_lease(struct inode *inode, unsigned int mode) |
1113 | { |
1114 | int error = 0, future; |
1115 | struct file_lock *new_fl, *flock; |
1116 | struct file_lock *fl; |
1117 | int alloc_err; |
1118 | unsigned long break_time; |
1119 | int i_have_this_lease = 0; |
1120 | |
1121 | alloc_err = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK, |
1122 | &new_fl); |
1123 | |
1124 | lock_kernel(); |
1125 | |
1126 | time_out_leases(inode); |
1127 | |
1128 | flock = inode->i_flock; |
1129 | if ((flock == NULL) || !IS_LEASE(flock)) |
1130 | goto out; |
1131 | |
1132 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) |
1133 | if (fl->fl_owner == current->files) |
1134 | i_have_this_lease = 1; |
1135 | |
1136 | if (mode & FMODE_WRITE) { |
1137 | /* If we want write access, we have to revoke any lease. */ |
1138 | future = F_UNLCK | F_INPROGRESS; |
1139 | } else if (flock->fl_type & F_INPROGRESS) { |
1140 | /* If the lease is already being broken, we just leave it */ |
1141 | future = flock->fl_type; |
1142 | } else if (flock->fl_type & F_WRLCK) { |
1143 | /* Downgrade the exclusive lease to a read-only lease. */ |
1144 | future = F_RDLCK | F_INPROGRESS; |
1145 | } else { |
1146 | /* the existing lease was read-only, so we can read too. */ |
1147 | goto out; |
1148 | } |
1149 | |
1150 | if (alloc_err && !i_have_this_lease && ((mode & O_NONBLOCK) == 0)) { |
1151 | error = alloc_err; |
1152 | goto out; |
1153 | } |
1154 | |
1155 | break_time = 0; |
1156 | if (lease_break_time > 0) { |
1157 | break_time = jiffies + lease_break_time * HZ; |
1158 | if (break_time == 0) |
1159 | break_time++; /* so that 0 means no break time */ |
1160 | } |
1161 | |
1162 | for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) { |
1163 | if (fl->fl_type != future) { |
1164 | fl->fl_type = future; |
1165 | fl->fl_break_time = break_time; |
1166 | /* lease must have lmops break callback */ |
1167 | fl->fl_lmops->fl_break(fl); |
1168 | } |
1169 | } |
1170 | |
1171 | if (i_have_this_lease || (mode & O_NONBLOCK)) { |
1172 | error = -EWOULDBLOCK; |
1173 | goto out; |
1174 | } |
1175 | |
1176 | restart: |
1177 | break_time = flock->fl_break_time; |
1178 | if (break_time != 0) { |
1179 | break_time -= jiffies; |
1180 | if (break_time == 0) |
1181 | break_time++; |
1182 | } |
1183 | error = locks_block_on_timeout(flock, new_fl, break_time); |
1184 | if (error >= 0) { |
1185 | if (error == 0) |
1186 | time_out_leases(inode); |
1187 | /* Wait for the next lease that has not been broken yet */ |
1188 | for (flock = inode->i_flock; flock && IS_LEASE(flock); |
1189 | flock = flock->fl_next) { |
1190 | if (flock->fl_type & F_INPROGRESS) |
1191 | goto restart; |
1192 | } |
1193 | error = 0; |
1194 | } |
1195 | |
1196 | out: |
1197 | unlock_kernel(); |
1198 | if (!alloc_err) |
1199 | locks_free_lock(new_fl); |
1200 | return error; |
1201 | } |
1202 | |
1203 | EXPORT_SYMBOL(__break_lease); |
1204 | |
1205 | /** |
1206 | * lease_get_mtime |
1207 | * @inode: the inode |
1208 | * @time: pointer to a timespec which will contain the last modified time |
1209 | * |
1210 | * This is to force NFS clients to flush their caches for files with |
1211 | * exclusive leases. The justification is that if someone has an |
1212 | * exclusive lease, then they could be modifiying it. |
1213 | */ |
1214 | void lease_get_mtime(struct inode *inode, struct timespec *time) |
1215 | { |
1216 | struct file_lock *flock = inode->i_flock; |
1217 | if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK)) |
1218 | *time = current_fs_time(inode->i_sb); |
1219 | else |
1220 | *time = inode->i_mtime; |
1221 | } |
1222 | |
1223 | EXPORT_SYMBOL(lease_get_mtime); |
1224 | |
1225 | /** |
1226 | * fcntl_getlease - Enquire what lease is currently active |
1227 | * @filp: the file |
1228 | * |
1229 | * The value returned by this function will be one of |
1230 | * (if no lease break is pending): |
1231 | * |
1232 | * %F_RDLCK to indicate a shared lease is held. |
1233 | * |
1234 | * %F_WRLCK to indicate an exclusive lease is held. |
1235 | * |
1236 | * %F_UNLCK to indicate no lease is held. |
1237 | * |
1238 | * (if a lease break is pending): |
1239 | * |
1240 | * %F_RDLCK to indicate an exclusive lease needs to be |
1241 | * changed to a shared lease (or removed). |
1242 | * |
1243 | * %F_UNLCK to indicate the lease needs to be removed. |
1244 | * |
1245 | * XXX: sfr & willy disagree over whether F_INPROGRESS |
1246 | * should be returned to userspace. |
1247 | */ |
1248 | int fcntl_getlease(struct file *filp) |
1249 | { |
1250 | struct file_lock *fl; |
1251 | int type = F_UNLCK; |
1252 | |
1253 | lock_kernel(); |
1254 | time_out_leases(filp->f_dentry->d_inode); |
1255 | for (fl = filp->f_dentry->d_inode->i_flock; fl && IS_LEASE(fl); |
1256 | fl = fl->fl_next) { |
1257 | if (fl->fl_file == filp) { |
1258 | type = fl->fl_type & ~F_INPROGRESS; |
1259 | break; |
1260 | } |
1261 | } |
1262 | unlock_kernel(); |
1263 | return type; |
1264 | } |
1265 | |
1266 | /** |
1267 | * __setlease - sets a lease on an open file |
1268 | * @filp: file pointer |
1269 | * @arg: type of lease to obtain |
1270 | * @flp: input - file_lock to use, output - file_lock inserted |
1271 | * |
1272 | * The (input) flp->fl_lmops->fl_break function is required |
1273 | * by break_lease(). |
1274 | * |
1275 | * Called with kernel lock held. |
1276 | */ |
1277 | static int __setlease(struct file *filp, long arg, struct file_lock **flp) |
1278 | { |
1279 | struct file_lock *fl, **before, **my_before = NULL, *lease = *flp; |
1280 | struct dentry *dentry = filp->f_dentry; |
1281 | struct inode *inode = dentry->d_inode; |
1282 | int error, rdlease_count = 0, wrlease_count = 0; |
1283 | |
1284 | time_out_leases(inode); |
1285 | |
1286 | error = -EINVAL; |
1287 | if (!flp || !(*flp) || !(*flp)->fl_lmops || !(*flp)->fl_lmops->fl_break) |
1288 | goto out; |
1289 | |
1290 | error = -EAGAIN; |
1291 | if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0)) |
1292 | goto out; |
1293 | if ((arg == F_WRLCK) |
1294 | && ((atomic_read(&dentry->d_count) > 1) |
1295 | || (atomic_read(&inode->i_count) > 1))) |
1296 | goto out; |
1297 | |
1298 | /* |
1299 | * At this point, we know that if there is an exclusive |
1300 | * lease on this file, then we hold it on this filp |
1301 | * (otherwise our open of this file would have blocked). |
1302 | * And if we are trying to acquire an exclusive lease, |
1303 | * then the file is not open by anyone (including us) |
1304 | * except for this filp. |
1305 | */ |
1306 | for (before = &inode->i_flock; |
1307 | ((fl = *before) != NULL) && IS_LEASE(fl); |
1308 | before = &fl->fl_next) { |
1309 | if (lease->fl_lmops->fl_mylease(fl, lease)) |
1310 | my_before = before; |
1311 | else if (fl->fl_type == (F_INPROGRESS | F_UNLCK)) |
1312 | /* |
1313 | * Someone is in the process of opening this |
1314 | * file for writing so we may not take an |
1315 | * exclusive lease on it. |
1316 | */ |
1317 | wrlease_count++; |
1318 | else |
1319 | rdlease_count++; |
1320 | } |
1321 | |
1322 | if ((arg == F_RDLCK && (wrlease_count > 0)) || |
1323 | (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0))) |
1324 | goto out; |
1325 | |
1326 | if (my_before != NULL) { |
1327 | error = lease->fl_lmops->fl_change(my_before, arg); |
1328 | goto out; |
1329 | } |
1330 | |
1331 | error = 0; |
1332 | if (arg == F_UNLCK) |
1333 | goto out; |
1334 | |
1335 | error = -EINVAL; |
1336 | if (!leases_enable) |
1337 | goto out; |
1338 | |
1339 | error = lease_alloc(filp, arg, &fl); |
1340 | if (error) |
1341 | goto out; |
1342 | |
1343 | locks_copy_lock(fl, lease); |
1344 | |
1345 | locks_insert_lock(before, fl); |
1346 | |
1347 | *flp = fl; |
1348 | out: |
1349 | return error; |
1350 | } |
1351 | |
1352 | /** |
1353 | * setlease - sets a lease on an open file |
1354 | * @filp: file pointer |
1355 | * @arg: type of lease to obtain |
1356 | * @lease: file_lock to use |
1357 | * |
1358 | * Call this to establish a lease on the file. |
1359 | * The fl_lmops fl_break function is required by break_lease |
1360 | */ |
1361 | |
1362 | int setlease(struct file *filp, long arg, struct file_lock **lease) |
1363 | { |
1364 | struct dentry *dentry = filp->f_dentry; |
1365 | struct inode *inode = dentry->d_inode; |
1366 | int error; |
1367 | |
1368 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) |
1369 | return -EACCES; |
1370 | if (!S_ISREG(inode->i_mode)) |
1371 | return -EINVAL; |
1372 | error = security_file_lock(filp, arg); |
1373 | if (error) |
1374 | return error; |
1375 | |
1376 | lock_kernel(); |
1377 | error = __setlease(filp, arg, lease); |
1378 | unlock_kernel(); |
1379 | |
1380 | return error; |
1381 | } |
1382 | |
1383 | EXPORT_SYMBOL(setlease); |
1384 | |
1385 | /** |
1386 | * fcntl_setlease - sets a lease on an open file |
1387 | * @fd: open file descriptor |
1388 | * @filp: file pointer |
1389 | * @arg: type of lease to obtain |
1390 | * |
1391 | * Call this fcntl to establish a lease on the file. |
1392 | * Note that you also need to call %F_SETSIG to |
1393 | * receive a signal when the lease is broken. |
1394 | */ |
1395 | int fcntl_setlease(unsigned int fd, struct file *filp, long arg) |
1396 | { |
1397 | struct file_lock fl, *flp = &fl; |
1398 | struct dentry *dentry = filp->f_dentry; |
1399 | struct inode *inode = dentry->d_inode; |
1400 | int error; |
1401 | |
1402 | if ((current->fsuid != inode->i_uid) && !capable(CAP_LEASE)) |
1403 | return -EACCES; |
1404 | if (!S_ISREG(inode->i_mode)) |
1405 | return -EINVAL; |
1406 | error = security_file_lock(filp, arg); |
1407 | if (error) |
1408 | return error; |
1409 | |
1410 | locks_init_lock(&fl); |
1411 | error = lease_init(filp, arg, &fl); |
1412 | if (error) |
1413 | return error; |
1414 | |
1415 | lock_kernel(); |
1416 | |
1417 | error = __setlease(filp, arg, &flp); |
1418 | if (error) |
1419 | goto out_unlock; |
1420 | |
1421 | error = fasync_helper(fd, filp, 1, &flp->fl_fasync); |
1422 | if (error < 0) { |
1423 | /* remove lease just inserted by __setlease */ |
1424 | flp->fl_type = F_UNLCK | F_INPROGRESS; |
1425 | flp->fl_break_time = jiffies- 10; |
1426 | time_out_leases(inode); |
1427 | goto out_unlock; |
1428 | } |
1429 | |
1430 | error = f_setown(filp, current->pid, 0); |
1431 | out_unlock: |
1432 | unlock_kernel(); |
1433 | return error; |
1434 | } |
1435 | |
1436 | /** |
1437 | * flock_lock_file_wait - Apply a FLOCK-style lock to a file |
1438 | * @filp: The file to apply the lock to |
1439 | * @fl: The lock to be applied |
1440 | * |
1441 | * Add a FLOCK style lock to a file. |
1442 | */ |
1443 | int flock_lock_file_wait(struct file *filp, struct file_lock *fl) |
1444 | { |
1445 | int error; |
1446 | might_sleep(); |
1447 | for (;;) { |
1448 | error = flock_lock_file(filp, fl); |
1449 | if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP)) |
1450 | break; |
1451 | error = wait_event_interruptible(fl->fl_wait, !fl->fl_next); |
1452 | if (!error) |
1453 | continue; |
1454 | |
1455 | locks_delete_block(fl); |
1456 | break; |
1457 | } |
1458 | return error; |
1459 | } |
1460 | |
1461 | EXPORT_SYMBOL(flock_lock_file_wait); |
1462 | |
1463 | /** |
1464 | * sys_flock: - flock() system call. |
1465 | * @fd: the file descriptor to lock. |
1466 | * @cmd: the type of lock to apply. |
1467 | * |
1468 | * Apply a %FL_FLOCK style lock to an open file descriptor. |
1469 | * The @cmd can be one of |
1470 | * |
1471 | * %LOCK_SH -- a shared lock. |
1472 | * |
1473 | * %LOCK_EX -- an exclusive lock. |
1474 | * |
1475 | * %LOCK_UN -- remove an existing lock. |
1476 | * |
1477 | * %LOCK_MAND -- a `mandatory' flock. This exists to emulate Windows Share Modes. |
1478 | * |
1479 | * %LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other |
1480 | * processes read and write access respectively. |
1481 | */ |
1482 | asmlinkage long sys_flock(unsigned int fd, unsigned int cmd) |
1483 | { |
1484 | struct file *filp; |
1485 | struct file_lock *lock; |
1486 | int can_sleep, unlock; |
1487 | int error; |
1488 | |
1489 | error = -EBADF; |
1490 | filp = fget(fd); |
1491 | if (!filp) |
1492 | goto out; |
1493 | |
1494 | can_sleep = !(cmd & LOCK_NB); |
1495 | cmd &= ~LOCK_NB; |
1496 | unlock = (cmd == LOCK_UN); |
1497 | |
1498 | if (!unlock && !(cmd & LOCK_MAND) && !(filp->f_mode & 3)) |
1499 | goto out_putf; |
1500 | |
1501 | error = flock_make_lock(filp, &lock, cmd); |
1502 | if (error) |
1503 | goto out_putf; |
1504 | if (can_sleep) |
1505 | lock->fl_flags |= FL_SLEEP; |
1506 | |
1507 | error = security_file_lock(filp, cmd); |
1508 | if (error) |
1509 | goto out_free; |
1510 | |
1511 | if (filp->f_op && filp->f_op->flock) |
1512 | error = filp->f_op->flock(filp, |
1513 | (can_sleep) ? F_SETLKW : F_SETLK, |
1514 | lock); |
1515 | else |
1516 | error = flock_lock_file_wait(filp, lock); |
1517 | |
1518 | out_free: |
1519 | if (list_empty(&lock->fl_link)) { |
1520 | locks_free_lock(lock); |
1521 | } |
1522 | |
1523 | out_putf: |
1524 | fput(filp); |
1525 | out: |
1526 | return error; |
1527 | } |
1528 | |
1529 | /* Report the first existing lock that would conflict with l. |
1530 | * This implements the F_GETLK command of fcntl(). |
1531 | */ |
1532 | int fcntl_getlk(struct file *filp, struct flock __user *l) |
1533 | { |
1534 | struct file_lock *fl, file_lock; |
1535 | struct flock flock; |
1536 | int error; |
1537 | |
1538 | error = -EFAULT; |
1539 | if (copy_from_user(&flock, l, sizeof(flock))) |
1540 | goto out; |
1541 | error = -EINVAL; |
1542 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) |
1543 | goto out; |
1544 | |
1545 | error = flock_to_posix_lock(filp, &file_lock, &flock); |
1546 | if (error) |
1547 | goto out; |
1548 | |
1549 | if (filp->f_op && filp->f_op->lock) { |
1550 | error = filp->f_op->lock(filp, F_GETLK, &file_lock); |
1551 | if (error < 0) |
1552 | goto out; |
1553 | else |
1554 | fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); |
1555 | } else { |
1556 | fl = posix_test_lock(filp, &file_lock); |
1557 | } |
1558 | |
1559 | flock.l_type = F_UNLCK; |
1560 | if (fl != NULL) { |
1561 | flock.l_pid = fl->fl_pid; |
1562 | #if BITS_PER_LONG == 32 |
1563 | /* |
1564 | * Make sure we can represent the posix lock via |
1565 | * legacy 32bit flock. |
1566 | */ |
1567 | error = -EOVERFLOW; |
1568 | if (fl->fl_start > OFFT_OFFSET_MAX) |
1569 | goto out; |
1570 | if ((fl->fl_end != OFFSET_MAX) |
1571 | && (fl->fl_end > OFFT_OFFSET_MAX)) |
1572 | goto out; |
1573 | #endif |
1574 | flock.l_start = fl->fl_start; |
1575 | flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : |
1576 | fl->fl_end - fl->fl_start + 1; |
1577 | flock.l_whence = 0; |
1578 | flock.l_type = fl->fl_type; |
1579 | } |
1580 | error = -EFAULT; |
1581 | if (!copy_to_user(l, &flock, sizeof(flock))) |
1582 | error = 0; |
1583 | out: |
1584 | return error; |
1585 | } |
1586 | |
1587 | /* Apply the lock described by l to an open file descriptor. |
1588 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
1589 | */ |
1590 | int fcntl_setlk(struct file *filp, unsigned int cmd, struct flock __user *l) |
1591 | { |
1592 | struct file_lock *file_lock = locks_alloc_lock(); |
1593 | struct flock flock; |
1594 | struct inode *inode; |
1595 | int error; |
1596 | |
1597 | if (file_lock == NULL) |
1598 | return -ENOLCK; |
1599 | |
1600 | /* |
1601 | * This might block, so we do it before checking the inode. |
1602 | */ |
1603 | error = -EFAULT; |
1604 | if (copy_from_user(&flock, l, sizeof(flock))) |
1605 | goto out; |
1606 | |
1607 | inode = filp->f_dentry->d_inode; |
1608 | |
1609 | /* Don't allow mandatory locks on files that may be memory mapped |
1610 | * and shared. |
1611 | */ |
1612 | if (IS_MANDLOCK(inode) && |
1613 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && |
1614 | mapping_writably_mapped(filp->f_mapping)) { |
1615 | error = -EAGAIN; |
1616 | goto out; |
1617 | } |
1618 | |
1619 | error = flock_to_posix_lock(filp, file_lock, &flock); |
1620 | if (error) |
1621 | goto out; |
1622 | if (cmd == F_SETLKW) { |
1623 | file_lock->fl_flags |= FL_SLEEP; |
1624 | } |
1625 | |
1626 | error = -EBADF; |
1627 | switch (flock.l_type) { |
1628 | case F_RDLCK: |
1629 | if (!(filp->f_mode & FMODE_READ)) |
1630 | goto out; |
1631 | break; |
1632 | case F_WRLCK: |
1633 | if (!(filp->f_mode & FMODE_WRITE)) |
1634 | goto out; |
1635 | break; |
1636 | case F_UNLCK: |
1637 | break; |
1638 | default: |
1639 | error = -EINVAL; |
1640 | goto out; |
1641 | } |
1642 | |
1643 | error = security_file_lock(filp, file_lock->fl_type); |
1644 | if (error) |
1645 | goto out; |
1646 | |
1647 | if (filp->f_op && filp->f_op->lock != NULL) { |
1648 | error = filp->f_op->lock(filp, cmd, file_lock); |
1649 | goto out; |
1650 | } |
1651 | |
1652 | for (;;) { |
1653 | error = __posix_lock_file(inode, file_lock); |
1654 | if ((error != -EAGAIN) || (cmd == F_SETLK)) |
1655 | break; |
1656 | error = wait_event_interruptible(file_lock->fl_wait, |
1657 | !file_lock->fl_next); |
1658 | if (!error) |
1659 | continue; |
1660 | |
1661 | locks_delete_block(file_lock); |
1662 | break; |
1663 | } |
1664 | |
1665 | out: |
1666 | locks_free_lock(file_lock); |
1667 | return error; |
1668 | } |
1669 | |
1670 | #if BITS_PER_LONG == 32 |
1671 | /* Report the first existing lock that would conflict with l. |
1672 | * This implements the F_GETLK command of fcntl(). |
1673 | */ |
1674 | int fcntl_getlk64(struct file *filp, struct flock64 __user *l) |
1675 | { |
1676 | struct file_lock *fl, file_lock; |
1677 | struct flock64 flock; |
1678 | int error; |
1679 | |
1680 | error = -EFAULT; |
1681 | if (copy_from_user(&flock, l, sizeof(flock))) |
1682 | goto out; |
1683 | error = -EINVAL; |
1684 | if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK)) |
1685 | goto out; |
1686 | |
1687 | error = flock64_to_posix_lock(filp, &file_lock, &flock); |
1688 | if (error) |
1689 | goto out; |
1690 | |
1691 | if (filp->f_op && filp->f_op->lock) { |
1692 | error = filp->f_op->lock(filp, F_GETLK, &file_lock); |
1693 | if (error < 0) |
1694 | goto out; |
1695 | else |
1696 | fl = (file_lock.fl_type == F_UNLCK ? NULL : &file_lock); |
1697 | } else { |
1698 | fl = posix_test_lock(filp, &file_lock); |
1699 | } |
1700 | |
1701 | flock.l_type = F_UNLCK; |
1702 | if (fl != NULL) { |
1703 | flock.l_pid = fl->fl_pid; |
1704 | flock.l_start = fl->fl_start; |
1705 | flock.l_len = fl->fl_end == OFFSET_MAX ? 0 : |
1706 | fl->fl_end - fl->fl_start + 1; |
1707 | flock.l_whence = 0; |
1708 | flock.l_type = fl->fl_type; |
1709 | } |
1710 | error = -EFAULT; |
1711 | if (!copy_to_user(l, &flock, sizeof(flock))) |
1712 | error = 0; |
1713 | |
1714 | out: |
1715 | return error; |
1716 | } |
1717 | |
1718 | /* Apply the lock described by l to an open file descriptor. |
1719 | * This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
1720 | */ |
1721 | int fcntl_setlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l) |
1722 | { |
1723 | struct file_lock *file_lock = locks_alloc_lock(); |
1724 | struct flock64 flock; |
1725 | struct inode *inode; |
1726 | int error; |
1727 | |
1728 | if (file_lock == NULL) |
1729 | return -ENOLCK; |
1730 | |
1731 | /* |
1732 | * This might block, so we do it before checking the inode. |
1733 | */ |
1734 | error = -EFAULT; |
1735 | if (copy_from_user(&flock, l, sizeof(flock))) |
1736 | goto out; |
1737 | |
1738 | inode = filp->f_dentry->d_inode; |
1739 | |
1740 | /* Don't allow mandatory locks on files that may be memory mapped |
1741 | * and shared. |
1742 | */ |
1743 | if (IS_MANDLOCK(inode) && |
1744 | (inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID && |
1745 | mapping_writably_mapped(filp->f_mapping)) { |
1746 | error = -EAGAIN; |
1747 | goto out; |
1748 | } |
1749 | |
1750 | error = flock64_to_posix_lock(filp, file_lock, &flock); |
1751 | if (error) |
1752 | goto out; |
1753 | if (cmd == F_SETLKW64) { |
1754 | file_lock->fl_flags |= FL_SLEEP; |
1755 | } |
1756 | |
1757 | error = -EBADF; |
1758 | switch (flock.l_type) { |
1759 | case F_RDLCK: |
1760 | if (!(filp->f_mode & FMODE_READ)) |
1761 | goto out; |
1762 | break; |
1763 | case F_WRLCK: |
1764 | if (!(filp->f_mode & FMODE_WRITE)) |
1765 | goto out; |
1766 | break; |
1767 | case F_UNLCK: |
1768 | break; |
1769 | default: |
1770 | error = -EINVAL; |
1771 | goto out; |
1772 | } |
1773 | |
1774 | error = security_file_lock(filp, file_lock->fl_type); |
1775 | if (error) |
1776 | goto out; |
1777 | |
1778 | if (filp->f_op && filp->f_op->lock != NULL) { |
1779 | error = filp->f_op->lock(filp, cmd, file_lock); |
1780 | goto out; |
1781 | } |
1782 | |
1783 | for (;;) { |
1784 | error = __posix_lock_file(inode, file_lock); |
1785 | if ((error != -EAGAIN) || (cmd == F_SETLK64)) |
1786 | break; |
1787 | error = wait_event_interruptible(file_lock->fl_wait, |
1788 | !file_lock->fl_next); |
1789 | if (!error) |
1790 | continue; |
1791 | |
1792 | locks_delete_block(file_lock); |
1793 | break; |
1794 | } |
1795 | |
1796 | out: |
1797 | locks_free_lock(file_lock); |
1798 | return error; |
1799 | } |
1800 | #endif /* BITS_PER_LONG == 32 */ |
1801 | |
1802 | /* |
1803 | * This function is called when the file is being removed |
1804 | * from the task's fd array. POSIX locks belonging to this task |
1805 | * are deleted at this time. |
1806 | */ |
1807 | void locks_remove_posix(struct file *filp, fl_owner_t owner) |
1808 | { |
1809 | struct file_lock lock, **before; |
1810 | |
1811 | /* |
1812 | * If there are no locks held on this file, we don't need to call |
1813 | * posix_lock_file(). Another process could be setting a lock on this |
1814 | * file at the same time, but we wouldn't remove that lock anyway. |
1815 | */ |
1816 | before = &filp->f_dentry->d_inode->i_flock; |
1817 | if (*before == NULL) |
1818 | return; |
1819 | |
1820 | lock.fl_type = F_UNLCK; |
1821 | lock.fl_flags = FL_POSIX; |
1822 | lock.fl_start = 0; |
1823 | lock.fl_end = OFFSET_MAX; |
1824 | lock.fl_owner = owner; |
1825 | lock.fl_pid = current->tgid; |
1826 | lock.fl_file = filp; |
1827 | lock.fl_ops = NULL; |
1828 | lock.fl_lmops = NULL; |
1829 | |
1830 | if (filp->f_op && filp->f_op->lock != NULL) { |
1831 | filp->f_op->lock(filp, F_SETLK, &lock); |
1832 | goto out; |
1833 | } |
1834 | |
1835 | /* Can't use posix_lock_file here; we need to remove it no matter |
1836 | * which pid we have. |
1837 | */ |
1838 | lock_kernel(); |
1839 | while (*before != NULL) { |
1840 | struct file_lock *fl = *before; |
1841 | if (IS_POSIX(fl) && posix_same_owner(fl, &lock)) { |
1842 | locks_delete_lock(before); |
1843 | continue; |
1844 | } |
1845 | before = &fl->fl_next; |
1846 | } |
1847 | unlock_kernel(); |
1848 | out: |
1849 | if (lock.fl_ops && lock.fl_ops->fl_release_private) |
1850 | lock.fl_ops->fl_release_private(&lock); |
1851 | } |
1852 | |
1853 | EXPORT_SYMBOL(locks_remove_posix); |
1854 | |
1855 | /* |
1856 | * This function is called on the last close of an open file. |
1857 | */ |
1858 | void locks_remove_flock(struct file *filp) |
1859 | { |
1860 | struct inode * inode = filp->f_dentry->d_inode; |
1861 | struct file_lock *fl; |
1862 | struct file_lock **before; |
1863 | |
1864 | if (!inode->i_flock) |
1865 | return; |
1866 | |
1867 | if (filp->f_op && filp->f_op->flock) { |
1868 | struct file_lock fl = { |
1869 | .fl_pid = current->tgid, |
1870 | .fl_file = filp, |
1871 | .fl_flags = FL_FLOCK, |
1872 | .fl_type = F_UNLCK, |
1873 | .fl_end = OFFSET_MAX, |
1874 | }; |
1875 | filp->f_op->flock(filp, F_SETLKW, &fl); |
1876 | } |
1877 | |
1878 | lock_kernel(); |
1879 | before = &inode->i_flock; |
1880 | |
1881 | while ((fl = *before) != NULL) { |
1882 | if (fl->fl_file == filp) { |
1883 | /* |
1884 | * We might have a POSIX lock that was created at the same time |
1885 | * the filp was closed for the last time. Just remove that too, |
1886 | * regardless of ownership, since nobody can own it. |
1887 | */ |
1888 | if (IS_FLOCK(fl) || IS_POSIX(fl)) { |
1889 | locks_delete_lock(before); |
1890 | continue; |
1891 | } |
1892 | if (IS_LEASE(fl)) { |
1893 | lease_modify(before, F_UNLCK); |
1894 | continue; |
1895 | } |
1896 | /* What? */ |
1897 | BUG(); |
1898 | } |
1899 | before = &fl->fl_next; |
1900 | } |
1901 | unlock_kernel(); |
1902 | } |
1903 | |
1904 | /** |
1905 | * posix_block_lock - blocks waiting for a file lock |
1906 | * @blocker: the lock which is blocking |
1907 | * @waiter: the lock which conflicts and has to wait |
1908 | * |
1909 | * lockd needs to block waiting for locks. |
1910 | */ |
1911 | void |
1912 | posix_block_lock(struct file_lock *blocker, struct file_lock *waiter) |
1913 | { |
1914 | locks_insert_block(blocker, waiter); |
1915 | } |
1916 | |
1917 | EXPORT_SYMBOL(posix_block_lock); |
1918 | |
1919 | /** |
1920 | * posix_unblock_lock - stop waiting for a file lock |
1921 | * @filp: how the file was opened |
1922 | * @waiter: the lock which was waiting |
1923 | * |
1924 | * lockd needs to block waiting for locks. |
1925 | */ |
1926 | void |
1927 | posix_unblock_lock(struct file *filp, struct file_lock *waiter) |
1928 | { |
1929 | /* |
1930 | * A remote machine may cancel the lock request after it's been |
1931 | * granted locally. If that happens, we need to delete the lock. |
1932 | */ |
1933 | lock_kernel(); |
1934 | if (waiter->fl_next) { |
1935 | __locks_delete_block(waiter); |
1936 | unlock_kernel(); |
1937 | } else { |
1938 | unlock_kernel(); |
1939 | waiter->fl_type = F_UNLCK; |
1940 | posix_lock_file(filp, waiter); |
1941 | } |
1942 | } |
1943 | |
1944 | EXPORT_SYMBOL(posix_unblock_lock); |
1945 | |
1946 | static void lock_get_status(char* out, struct file_lock *fl, int id, char *pfx) |
1947 | { |
1948 | struct inode *inode = NULL; |
1949 | |
1950 | if (fl->fl_file != NULL) |
1951 | inode = fl->fl_file->f_dentry->d_inode; |
1952 | |
1953 | out += sprintf(out, "%d:%s ", id, pfx); |
1954 | if (IS_POSIX(fl)) { |
1955 | out += sprintf(out, "%6s %s ", |
1956 | (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ", |
1957 | (inode == NULL) ? "*NOINODE*" : |
1958 | (IS_MANDLOCK(inode) && |
1959 | (inode->i_mode & (S_IXGRP | S_ISGID)) == S_ISGID) ? |
1960 | "MANDATORY" : "ADVISORY "); |
1961 | } else if (IS_FLOCK(fl)) { |
1962 | if (fl->fl_type & LOCK_MAND) { |
1963 | out += sprintf(out, "FLOCK MSNFS "); |
1964 | } else { |
1965 | out += sprintf(out, "FLOCK ADVISORY "); |
1966 | } |
1967 | } else if (IS_LEASE(fl)) { |
1968 | out += sprintf(out, "LEASE "); |
1969 | if (fl->fl_type & F_INPROGRESS) |
1970 | out += sprintf(out, "BREAKING "); |
1971 | else if (fl->fl_file) |
1972 | out += sprintf(out, "ACTIVE "); |
1973 | else |
1974 | out += sprintf(out, "BREAKER "); |
1975 | } else { |
1976 | out += sprintf(out, "UNKNOWN UNKNOWN "); |
1977 | } |
1978 | if (fl->fl_type & LOCK_MAND) { |
1979 | out += sprintf(out, "%s ", |
1980 | (fl->fl_type & LOCK_READ) |
1981 | ? (fl->fl_type & LOCK_WRITE) ? "RW " : "READ " |
1982 | : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE "); |
1983 | } else { |
1984 | out += sprintf(out, "%s ", |
1985 | (fl->fl_type & F_INPROGRESS) |
1986 | ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ " |
1987 | : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ "); |
1988 | } |
1989 | if (inode) { |
1990 | #ifdef WE_CAN_BREAK_LSLK_NOW |
1991 | out += sprintf(out, "%d %s:%ld ", fl->fl_pid, |
1992 | inode->i_sb->s_id, inode->i_ino); |
1993 | #else |
1994 | /* userspace relies on this representation of dev_t ;-( */ |
1995 | out += sprintf(out, "%d %02x:%02x:%ld ", fl->fl_pid, |
1996 | MAJOR(inode->i_sb->s_dev), |
1997 | MINOR(inode->i_sb->s_dev), inode->i_ino); |
1998 | #endif |
1999 | } else { |
2000 | out += sprintf(out, "%d <none>:0 ", fl->fl_pid); |
2001 | } |
2002 | if (IS_POSIX(fl)) { |
2003 | if (fl->fl_end == OFFSET_MAX) |
2004 | out += sprintf(out, "%Ld EOF\n", fl->fl_start); |
2005 | else |
2006 | out += sprintf(out, "%Ld %Ld\n", fl->fl_start, |
2007 | fl->fl_end); |
2008 | } else { |
2009 | out += sprintf(out, "0 EOF\n"); |
2010 | } |
2011 | } |
2012 | |
2013 | static void move_lock_status(char **p, off_t* pos, off_t offset) |
2014 | { |
2015 | int len; |
2016 | len = strlen(*p); |
2017 | if(*pos >= offset) { |
2018 | /* the complete line is valid */ |
2019 | *p += len; |
2020 | *pos += len; |
2021 | return; |
2022 | } |
2023 | if(*pos+len > offset) { |
2024 | /* use the second part of the line */ |
2025 | int i = offset-*pos; |
2026 | memmove(*p,*p+i,len-i); |
2027 | *p += len-i; |
2028 | *pos += len; |
2029 | return; |
2030 | } |
2031 | /* discard the complete line */ |
2032 | *pos += len; |
2033 | } |
2034 | |
2035 | /** |
2036 | * get_locks_status - reports lock usage in /proc/locks |
2037 | * @buffer: address in userspace to write into |
2038 | * @start: ? |
2039 | * @offset: how far we are through the buffer |
2040 | * @length: how much to read |
2041 | */ |
2042 | |
2043 | int get_locks_status(char *buffer, char **start, off_t offset, int length) |
2044 | { |
2045 | struct list_head *tmp; |
2046 | char *q = buffer; |
2047 | off_t pos = 0; |
2048 | int i = 0; |
2049 | |
2050 | lock_kernel(); |
2051 | list_for_each(tmp, &file_lock_list) { |
2052 | struct list_head *btmp; |
2053 | struct file_lock *fl = list_entry(tmp, struct file_lock, fl_link); |
2054 | lock_get_status(q, fl, ++i, ""); |
2055 | move_lock_status(&q, &pos, offset); |
2056 | |
2057 | if(pos >= offset+length) |
2058 | goto done; |
2059 | |
2060 | list_for_each(btmp, &fl->fl_block) { |
2061 | struct file_lock *bfl = list_entry(btmp, |
2062 | struct file_lock, fl_block); |
2063 | lock_get_status(q, bfl, i, " ->"); |
2064 | move_lock_status(&q, &pos, offset); |
2065 | |
2066 | if(pos >= offset+length) |
2067 | goto done; |
2068 | } |
2069 | } |
2070 | done: |
2071 | unlock_kernel(); |
2072 | *start = buffer; |
2073 | if(q-buffer < length) |
2074 | return (q-buffer); |
2075 | return length; |
2076 | } |
2077 | |
2078 | /** |
2079 | * lock_may_read - checks that the region is free of locks |
2080 | * @inode: the inode that is being read |
2081 | * @start: the first byte to read |
2082 | * @len: the number of bytes to read |
2083 | * |
2084 | * Emulates Windows locking requirements. Whole-file |
2085 | * mandatory locks (share modes) can prohibit a read and |
2086 | * byte-range POSIX locks can prohibit a read if they overlap. |
2087 | * |
2088 | * N.B. this function is only ever called |
2089 | * from knfsd and ownership of locks is never checked. |
2090 | */ |
2091 | int lock_may_read(struct inode *inode, loff_t start, unsigned long len) |
2092 | { |
2093 | struct file_lock *fl; |
2094 | int result = 1; |
2095 | lock_kernel(); |
2096 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
2097 | if (IS_POSIX(fl)) { |
2098 | if (fl->fl_type == F_RDLCK) |
2099 | continue; |
2100 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) |
2101 | continue; |
2102 | } else if (IS_FLOCK(fl)) { |
2103 | if (!(fl->fl_type & LOCK_MAND)) |
2104 | continue; |
2105 | if (fl->fl_type & LOCK_READ) |
2106 | continue; |
2107 | } else |
2108 | continue; |
2109 | result = 0; |
2110 | break; |
2111 | } |
2112 | unlock_kernel(); |
2113 | return result; |
2114 | } |
2115 | |
2116 | EXPORT_SYMBOL(lock_may_read); |
2117 | |
2118 | /** |
2119 | * lock_may_write - checks that the region is free of locks |
2120 | * @inode: the inode that is being written |
2121 | * @start: the first byte to write |
2122 | * @len: the number of bytes to write |
2123 | * |
2124 | * Emulates Windows locking requirements. Whole-file |
2125 | * mandatory locks (share modes) can prohibit a write and |
2126 | * byte-range POSIX locks can prohibit a write if they overlap. |
2127 | * |
2128 | * N.B. this function is only ever called |
2129 | * from knfsd and ownership of locks is never checked. |
2130 | */ |
2131 | int lock_may_write(struct inode *inode, loff_t start, unsigned long len) |
2132 | { |
2133 | struct file_lock *fl; |
2134 | int result = 1; |
2135 | lock_kernel(); |
2136 | for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) { |
2137 | if (IS_POSIX(fl)) { |
2138 | if ((fl->fl_end < start) || (fl->fl_start > (start + len))) |
2139 | continue; |
2140 | } else if (IS_FLOCK(fl)) { |
2141 | if (!(fl->fl_type & LOCK_MAND)) |
2142 | continue; |
2143 | if (fl->fl_type & LOCK_WRITE) |
2144 | continue; |
2145 | } else |
2146 | continue; |
2147 | result = 0; |
2148 | break; |
2149 | } |
2150 | unlock_kernel(); |
2151 | return result; |
2152 | } |
2153 | |
2154 | EXPORT_SYMBOL(lock_may_write); |
2155 | |
2156 | static inline void __steal_locks(struct file *file, fl_owner_t from) |
2157 | { |
2158 | struct inode *inode = file->f_dentry->d_inode; |
2159 | struct file_lock *fl = inode->i_flock; |
2160 | |
2161 | while (fl) { |
2162 | if (fl->fl_file == file && fl->fl_owner == from) |
2163 | fl->fl_owner = current->files; |
2164 | fl = fl->fl_next; |
2165 | } |
2166 | } |
2167 | |
2168 | /* When getting ready for executing a binary, we make sure that current |
2169 | * has a files_struct on its own. Before dropping the old files_struct, |
2170 | * we take over ownership of all locks for all file descriptors we own. |
2171 | * Note that we may accidentally steal a lock for a file that a sibling |
2172 | * has created since the unshare_files() call. |
2173 | */ |
2174 | void steal_locks(fl_owner_t from) |
2175 | { |
2176 | struct files_struct *files = current->files; |
2177 | int i, j; |
2178 | |
2179 | if (from == files) |
2180 | return; |
2181 | |
2182 | lock_kernel(); |
2183 | j = 0; |
2184 | for (;;) { |
2185 | unsigned long set; |
2186 | i = j * __NFDBITS; |
2187 | if (i >= files->max_fdset || i >= files->max_fds) |
2188 | break; |
2189 | set = files->open_fds->fds_bits[j++]; |
2190 | while (set) { |
2191 | if (set & 1) { |
2192 | struct file *file = files->fd[i]; |
2193 | if (file) |
2194 | __steal_locks(file, from); |
2195 | } |
2196 | i++; |
2197 | set >>= 1; |
2198 | } |
2199 | } |
2200 | unlock_kernel(); |
2201 | } |
2202 | EXPORT_SYMBOL(steal_locks); |
2203 | |
2204 | static int __init filelock_init(void) |
2205 | { |
2206 | filelock_cache = kmem_cache_create("file_lock_cache", |
2207 | sizeof(struct file_lock), 0, SLAB_PANIC, |
2208 | init_once, NULL); |
2209 | return 0; |
2210 | } |
2211 | |
2212 | core_initcall(filelock_init); |